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Патент USA US2108822

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Feb. 22', 1938.
2,108,822
w. A. LIPPINCOTT
PRINTING PLATE AND FORMATION THEREOF
Filed Nov. 11, 1955
3 Sheets-Sheet l
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Feb. 22, 1938‘.
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w; A. LiPPlNCOTT
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2,108,822
.PRINTING PLATE AND'FORMATION THEREOF
Filed Nov. 11, 1935 _
3 Sheets-Sheet 2
////////////A/ // III
Feb. 22, 1938.
2,108,822
W. A. LIPPINCOTT
PRINTING PLATE AND ‘FORMATION THEREOF
Filed Nov. 11, 1955
s ‘Sheets-Sheet 3
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Patented Feb. 22, 1938
‘2,108,822 -
gUNlTED STATES PATENT OFFICE‘.
‘PRINTING PLATE AND FORMATION
THEREOF
Wells A. Lippincott, Chicago, Ill.
Application November 11, 1935, Serial No. 49,186
7 Claims. ( Cl. 41—25)
This invention relates in general to printing
plates and the formation and mounting thereof
and more particularly to printing plates of the
kind in which all or part of the type projections
. 5
de?ning the printing surface are formed in a
molding operation.
‘present invention.
Fig. 11 is a cross-sectional ‘view showing a
modi?ed form of printing plate in the process of 5
manufacture.
One object of the invention is to simplify and
reduce the cost of manufacturing and mount
ing of printing surfaces by providing a printing
10 plate having type projections composed of read
ily moldable material capable of withstanding the
pressure encountered during printing and of being
bent readily to the curvature of the press sup
port upon which the plate is mounting during
16 printing. In carrying out this object, it is pre
ferred to employ a moldable material having
thermoplastic properties, that is to say, a mate
rial which after being initially molded will soften
gradually upon being heated.
Another object is to provide a novel mount
20
'
Fig. 12 is a cross-sectional view on a substan
tially enlarged scale illustrating a modi?ed form
of printing surface.
The invention is susceptible of various modi- 10
?cations and therefore I do not, by the present
exemplary disclosure, intend to limit the inven
tion but aim to cover all modi?cations and alter
natives falling within the spirit and scope of the
invention as expressed in the appended claims.
In the drawings, the invention is embodied for
purposes of illustration in a rectangularly shaped
printing plate generally indicated at 9 carrying
type II), the faces ll of which de?ne a surface
ing for a type surface of the above general char
for printing‘ part or all of one page of a magazine 20
or the like. In the present instance, the type are
acter.
in the form of solid projections integral with and
'
A further object is to provide a novel construc
tion of the different color plates for use in multi
25 color printing which permits exact color registra
tion to be obtained after bending thereof to con
form to curved printing press supports.
Another object is to provide a novel method by
which molded printing plates of the above char
30 acter may be formed to produce a high degree
of accuracy in the location of the printing sur
faces relative to the back surface of the plate.
The invention also aims to provide a novel
method of curving printing plates of the general
35 character referred to above.
,
Other objects and advantages of the inven
tion will become apparent from the following de
tailed description taken in connection with the
accompanying drawings, in which
40 ‘Figure 1 is a fragmentary perspective view of
a printing press cylinder equipped with a print
ing plate embodying the features of the present
invention, the plate being partially detached from
the cylinder.
45
Figs. 9 and 10 are views similar to Figs. '7 and
8 of plates constructed in accordance with the
Fig. 2 is a fragmentary sectional view illus
trating the arrangement of the parts preparatory
to molding of the printing plate.
Fig. 3 is a fragmentary sectional view of the
printing plate attached to a press cylinder.
Figs. 4, 5 and 6 are fragmentary sectional views
50
on a small scale illustrating the method of bend
ing the printing plate.
Figs. 7 and 8 are fragmentary cross-sectional
views on an enlarged scale of two different color
55 plates to be used in multi-color printing.
standing out in relief from a base or layer i2 com
posed of the same material as the type and of
uniform thickness. For reasons to appear later, 25
the layer I2 is made as thin as practicable and
yet thick enough to unit the type projections in
tegrally and enable the same to be secured prop
erly to a reinforcing member or carrying sheet l3.
The present invention contemplates formation 30
of the type II] and the layer l2 in whole or in part
of a readily moldable material which is sufficient
ly ductile or elastic to bend readily. Preferably,
the material has thermoplastic characteristics;
that is to say, will, after initial setting, soften
gradually upon being reheated. -A material
known to the trade as “Vinylite” and formed by
the polymerization of a vinyl compound has been
found to possess a degree of hardness sufficient
to withstand "the wear and tear incident to use in
the modern high speed printing press. By the
addition of well' known plasticizers, such for ex
ample as dibutylphthalate, the degree of duc
tility of the layer l2 may be varied as desired in
order to attain the required flexibility of the 45
printing plate as a whole.
The carrying sheet i3 serves to reinforce the
molded type layer and enable the same to be fas
tened detachably on the printing press support
14 and securely held thereon during printing. Cl C
Preferably, the sheet I3 is substantially thinner
than the base l2 and is composed of metal such
as steel possessing a relatively high degree of
?exibility and yet is substantially nonextensible
as compared to the type layer l2, that is, is ca 55
2
2,108,822
pable of withstanding a substantial edgewise ten
?uid through coils 28. During molding, the mold
sion and compression without appreciable change
is supported on the lower platen 25 and covered
in surface dimensions.
>
'
with a layer 26 of the resin ingredients in pow
The carrying sheet l3 and the molded type
layer l2 are ?rmly bonded together during the
dered or sheet form su?icient in amount to more
molding operation in which the type projections
plastic state. The carrying sheet l3 may be fas
tened to a filler plate 21 against which the upper
platen 24 acts. To prevent the resin from ad
hering to those parts of the carrying sheet corre
are formed. For this purpose, the upper surface
of the sheet is covered by and firmly cemented by
a suitable adhesive such as water glass to a sheet
l5 of muslin or other material to which the resin
will adhere readily.
The metal sheet affords a convenient medium
through which the printing plate may be
stretched over and securely but detachably fas
15 tened to a backing surface mounted on the print
ing press support l4. Herein, the backing surface
is formed by a plate [6 preferably preformed to
the curvature of the cylinder i4 and of a uni
form thickness sufficient to locate the printing
20 surfaces H in proper position with respect to
the cooperating impression cylinder of the print
ing press. In the embodiment shown, the back
ing plate comprises two substantially rigid plate
sections 11 and 18 connected in edge-to-edge re
25 lation at a hinge joint l9. The two opposite
edges of the backing plate are adapted to be
received between shoulders 20 formed along the
opposite side edges of the sheet l3 immediately
beyond the edges of the layer l2. These shoul
30' ders may be formed by bending the outermost
portions of the sheet 13 reversely on the under
side of the layer l2 so as to form inturned ?anges
2i.
In securing the printing plate to the press
cylinder through the medium of the backing
member above described, the plate section I‘! is
?rst clamped to the cylinder, the free edge of
the section I8 is swung upwardly and the printing
plate applied as shown in Fig. 1. Now, when the
-40 section 18 is pressed downwardly against the
cylinder, the plate will be expanded with a toggle
action as the sections l1 and I8 are brought into
edgewise alinement thereby stretching the sheet
13 and drawing the printing plate over the sur
face of the backing member and effectually se
curing the sheet ‘l4 and backing member to
gether. By applying clamps 22 to the free edge
of the backing section l8, the sheet and backing
member assembly will be securely fastened to the
press cylinder ready for printing.
The vinyl resin of vwhich the type are formed
in the printing plate above described possesses
certain properties which adapt the resin for such
use. The resin does not shrink as much in mold
ing as most synthetic resins and takes a sharp
impression. The thermoplastic character renders
the plate readily usable in rotary printing presses
sponding to the so-called dead metal areas of the 10
original form, a suitable mast l4‘1L may be inter
posed between the material 26 and the sheet I3.
With the parts thus assembled, the platens are
?rst maintained in close proximity to each other
until the resin has been softened properly. Then, 15
the platens are moved together under pressure
to compress the plastic ingredients to a thick
ness determined by bearers 28 after which the
resin is allowed to set.
Upon cooling, the ?nished plate may be 20
stripped from the mold and thereafter bent to
the proper curvature. This is accomplished by
reheating the printing plate to a temperature
su?icient to soften the resin slightly, bending the
plate around a cylindrical surface of slightly
smaller radius than the printing press support
on which the plate isto be used, and allowing
the bent plate to cool. If desired, such bending
may be effected by the same general method
which is used in attaching the printing plate to 30
the printing press cylinder. To this end, a back~
ing plate and cylinder as shown in Figs. 4 to 6
would be employed having a radius slightly small
er than the radius of curvature desired in the
finished plate. One ?ange of the reheated plate 35
would first be hooked around the backing plate
section ll as shown in Fig. 4 and the other end
then hooked around the section 18 as shown in
Fig. 5. By moving the sections 11 and I8 into
alinement as shown in Fig. 6, the carrying sheet 40
i3 is stretched over and bent around the backing
plate after which the plate is allowed to cool
and take a permanent set. By bending the plate
to a smaller radius than the printing press sup
port on which the plate is to operate, any slight 45
shrinkage which may occur upon cooling of the
resin is compensated for and the final curvature
desired thus obtained.
To avoid incorporation in the finished printing
plate of any inaccuracies that may exist in the 50
spacing of the platens of the press used in the
molding operation, the invention contemplates
treatment of a molded plate in a manner such as
to insure a high degree of accuracy in the spac
ing of the type surface with respect to the back
surface of the printing plate. This is accom
plished by machining the back surface of the
requiring a curved type surface. The plate above
carrying sheet l3 to locate the same exactly par
described possesses suf?cient ?exibility to respond
allel with respect to the printing surface I I of the
plate. To facilitate this operation, a thin layer
30 (Fig. 11) of lead or other readily machinable
metal is preferably sweated onto the underside
of the carrying sheet and shaved off to the proper
degree after the molding operation and while the
type projections are still supported by the 65
mold 23.
Preparatory to the machining operation, an ex
tended end portion 3| of the carrying sheet i3
is bent around a block 32 and securely fastened
70
60 to a detail make-ready placed beneath the back
ing member l6 instead of on the impression cyl
inder as is done in standard practice.
The printing plate is preferably formed in a
single molding operation from a mold 23 having
indentations therein corresponding to the type
to be formed and formed from an original en
graving or form in the manner disclosed in a
copending application of Arthur B. Davis, Serial
No. 736,222, ?led July 20, 1934.
The plate molding operation is carried on in
a suitable press preferably operated hydraulically
and having platens 24 and 25 heated to the tem
75
than ?ll all of the mold cavities when in the
by means of a clamping member 33.
Then, one
perature necessary for softening the resin in
or more passes across the layer 30 are made in a
well known manner with a shaving tool 34 to re
gredients to the degree required for molding.
This may be accomplished by circulating heating
to the proper degree and at the same time locate
duce the overall thickness of the printing plate
3
2,108,822
the machined surface accurately with respect to
referred to in the bending of the plate, and the
the printing surface formed by the type.
Theplate construction above described is par
ticularly advantageous for use in multi-color
printing in rotary printing presses, for with such
construction, perfect color register is obtainable
distance between this plane‘ and the type surface
for the different color plates is always the same
in spite of the bending which is necessary in or
der to adapt the different color plates to the cy
lindrical supports of rotary printing presses.
10 This advantageous characteristic of the present
plate construction may best be understood after
an appreciation of the'conditions causing uneven
distortion of the different color plates and lack
of color register in the matter printed thereby
15 when such plates are constructed of the same kind
' ‘ofv material throughout or comprise ordinary
lead-backed electrotypes. ~
241?
25
30
35
40
regardless of the character of the type surfaces.
Therefore, in bending of'the plate, the sheet I3
will actually cause the printing face of a large
solid type area to be stretched to a slight extent
and in the same proportion that the surfaces of
spaced dots will be separated in bending._ As a
result, the distance between two points on a large 1O
solid type area of one color plate will be in
creased in ‘bending to the same degree as the
distance between two similarly spaced points on a
different color plate having type projections of
small areas. Thus, by locating the sheets I3 of 15
the plates for printing different colors equidis
tant from the surface de?ned by the type, uni
form distortion of the typev surfaces of, all of
the plates results from bending.‘ Exact color
register, therefore, will be obtained when the two 20
Referring now to Figs. '7 to 10 which show two
printing plates 35 and 36 composed of one kind
of material throughout; the plate 35 has a type
surface 3‘l adapted to print a large solid area plates are used in multi-color printing.
of a length x. The plate 36 has type projections
The foregoing action will be more apparent
3t ‘separated by a distance 31 and intended to from Figs. 9 and 10 which show plates ‘til and iii _
print small widely separated areas in a different constructed in accordance with the present in
color with their inner edges in register with the vention and having type faces of the same shape 25
outer edges of the solid area printed by the type as the plates 35 and 36 shown in Figs. 7 and 8.
face 3?.
In both of the plates 30 and M , it will be observed
Itis well known that when a ?at plate of any that the distances 2 between the sheet I3 and
substantial thickness, such as the solid portion the type face are equal. When the plate 40 is
of the plate 35 is bent around a cylinder, the bent, the distance between the opposite side 30
material on the concave side is compressed while edges of the solid type area 42 is increased in the
ratio of
'
'
that on the convex surface is placed under ten
sion. The magnitude of the tension produced in
z-l-R
bending and therefore the increase in the dis
R
tance between opposite sides edges of the solid '
area 3? is proportional to the distance of the where R is the radius of curvature of the sheet I3.
The distance between the inner edges of the
surface from a neutral line 39 along which the projections
43 of the plate M will change in the
material is undisturbed. For a plate composed same ratio in bending. Since the distance 2 is
of one kind of material, this neutral line is lo
the same for both plates, the distances :0 and y
cated about midway between the opposite ‘side
surfaces of the plate. With a thinner plate, such
as that portion of the plate 36 between the pro
jections 38, the distance between the neutral line
38 and the surface of the type 38 is greater; con
45 sequently, the distance between the projections
will be increased in the same ratio so that when 40
the plates are used in multi-color printing, the
inner edges of the matter printed by theprojec
tions 43 will coincide exactly with the outer edges
of the solid area printed by the type face 42. In
this way, perfect color register is obtained with
as indicated at 1/ is increased more in bending of out treatment of the plates subsequent to bend
the plate ‘38 than the distance a: in the case of
the plate 35,. In othér words, if the distances at
Where extremely severe conditions prevail in
and y are equal‘ before bending, the distance 11/ service, it may be desirable toprotect the sur
50 will be greater after bending by an amount rep
' face of the type projections by covering the same
resented in Fig. 8 between the radial line r and with a thin shell of‘ metal of uniform thickness.
the inner edge of the adjacent projection 38. If In such a case, the resinous layer I2 and the pro
such plates were used in multi-color printing, the jections III would act as a ?ller for the cavities
adjacent edges of the solid area printed by the inthe back of the metallic shell forming the
55 surface 31 and the areas printed by the type 38
actual printing surface.
would be separated and proper color register
The life of the printing plate may also be pro
would. not be obtained.
longed by incorporating in the material of the
This deviation from proper register will be layer a ?ller which acts to increase the resistance
more pronounced where, as in the lead-backed
of the hardened resinous material to flowing
electrotypes ordinarily used in multi-color print
under the temperatures and stresses encountered
ing, the material forming the ?lling and backing during prolonged use of the plate in a high speed
for the electrotype shell is more readily com
printing press. Such ?ller may take various
pressible than the type face. With such a plate, forms and preferably constitutes a substantially
the metal forming the type surface would de?ne larger proportion of the moldable material than
65 the neutral plane in bending and the type surface the resinous binding ingredient. For example,
for printing a large solid area would remain prac
the ?ller may comprise granules 45 (Fig. 12) of
mg.
tically unstretched after bending; whereas, the
surfaces of widely spaced dots would, as an in
cident to bending, be seperated the same as in
70 the case of the plate 36 above described.
In a printing plate constructed in accordance
with the present invention, the sheet I3, being
composed of material which is non-compressible
as compared to the material of which the type
is composed, determines the neutral line above
.
~
.
50
60
.
65
a hard material such as metal, carborundum or
the like of such small size that in the molding
operation the “dots” 46 for obtaining the dif
ferent color shades may be reproduced accurately. 70
To this end, the particles of the aggregate or
?ller ingredient are preferably of a size capable
of passing a 300 mesh sieve or smaller and are
combined with a suii‘icient proportion of the
thermoplastic resin to insure that all of the voids 75
2,108,822
in the aggregate will be ?lled. When approxi
a layer of resin having type projections molded
used, it has been found that the resistance of the
composite material ?owing when cold may be
'in one side thereof and having thermoplastic
characteristics whereby to soften when reheated
increased approximately ten times. ‘According
ly, the service life of the plate may be increased
after molding and permit bending of the layer to
a predetermined curvature, and an integral sheet
materially.
of' metal secured to the other side of said layer
and acting during bending of the layer to define a
neutral plane of bending spaced equidistant from
all parts of the surface de?ned by said projec 10
tions whereby to cause uniform stretching of said
surface.
This application is a continuation in part of.
my former application Serial No. 605,418, filed
10
4. A printing plate comprising, in combination,
mately 28 percent of the binding ingredient is
April 15, 1932.
I claim as my invention:
1. For use in multi-color printing on a printing
press having cylindrieal'supports for the different
color plates, a plurality of plates for printing
different colors each comprising a ?exible sheet
of metal capable of withstanding edgewise com
pression and a layer of a thermoplastic resin,
said layer being secured to one side of said sheet
and having type formed therein, said sheets for
20 the different color plates being disposed substan
tially equidistant from the type surfaces and
operating to produce uniform distortion of said
surfaces in bending of said plates to adapt them
to the curvature of said supports.
2. For use in multi-color printing on a printing
press having cylindrical supports, a plurality of
plates for printing different colors each compris
ing a flexible metal sheet substantially non-com
pressible edgewise, and a layer composed of mate
30 rial which is su?iciently ductile to permit of
bending, said layer being carried by and united
with said sheet and having type standing out in
relief thereon and said sheets for the different
color plates being spaced substantially equi
35 distant from the type surfaces and de?ning neu
tral planes in the bending of the plates whereby
to produce exact color register in the use of the
different color plates after bending thereof to
conform to the convex curvature of said sup
ports.
‘
3.‘ For use in multi-color printing on a print
ing press having cylindrical supports for the dif
ferent color plates, a plurality of plates for print
ing different colors and each having type stand
45 ing out in relief therefrom, and means operable
to withstand edgewise compression during bend
ing of said plates and thereby determine neutral
planes of bending extending parallel to and
spaced substantially equidistant from said sur
60 faces whereby to cause uniform distortion of said
surfaces in the bending.
5. For use in a printing press having a curved
support, a printing plate assembly comprising a
layer of moldable thermoplastic material having
type projections molded in one side thereof, an
integral sheet of metal secured to said layer and
acting during bending thereof to de?ne a neutral
plane of bending spaced equidistant from all
parts of the surface defined by said projections 20
whereby to cause uniform stretching of said sur
face, fastening devices on opposite side portions
of said sheet, [and means on said support inter
engageable with said devices for placing said
sheet under tension whereby to stretch the sheet 25
over said support and thereby attach said layer
to the support.
'
-
6. The method of forming a curved printing
plate to be mounted on a printing press cylinder
comprising molding type projections in a layer 30
of material which will soften upon being heated,
bonding a flexible sheet of metal to the back of
said layer, heating the composite plate thus
formed to a temperature su?ieient to soften said
material, bending the plate, while thus heated, 35
around a surface corresponding in curvature to
but of smaller radius than said cylinder, and
allowing the bent plate to cool.
7. The method of forming a printing plate
comprising forming a mold having cavities there 40
in corresponding to the type to be formed, form
ing a type carrying sheet in said mold, uniting
said layer with a sheet of material which is sub
stantially non-extensible in an edgewise direc
tion, and machining the back of said sheet to par
allelism with the surface of said type while the
latter surface is backed by the mold and said
sheet is held against edgewise movement.
WELLS A. LIPPINCOTT.
50
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